Damper

ABSTRACT

The present invention includes a damper assembly, method and kit to provide dampening to an airframe comprising: a mass to dampen the vibration of the airframe; one or more wire rope isolators having a first and a second portion, wherein the mass is attached to the one or more wire rope isolators and the mass is isolated from the airframe by the one or more wire rope isolators; and a first fastener and a second fastener, wherein the first fasteners attaches to the first portion of the wire rope isolator to the mass, and the second fastener attaches the second portion of the wire rope isolator to the airframe to dampen vibration of the airframe.

CROSS-REFERENCE TO RELATED APPLICATIONS

None.

STATEMENT OF FEDERALLY FUNDED RESEARCH

None.

TECHNICAL FIELD OF THE INVENTION

The present invention relates in general to the field of dampers, andmore particularly, to a novel damper assembly.

BACKGROUND OF THE INVENTION

Without limiting the scope of the invention, its background is describedin connection with aircraft dampers.

One such patent is U.S. Pat. No. 8,622,375, issued to Bosworth, et al.and entitled, “Dual frequency damper for an aircraft”. Briefly, theseinventors teach a dual frequency damper includes a liquid inertiavibration eliminator (LIVE) portion and a fluid damper portion. The LIVEportion and fluid damper portion are said to operate in series andfunction so that dual frequency damper is optimized in both stiffnessand damping at multiple frequencies. LIVE portion acts as a frequencydependent switch to selectively cause low frequency oscillatory forcesto be treated primarily by the high spring rate and high damping ratecharacteristics of the fluid damper portion, and also to select highfrequency oscillatory forces to be primarily treated by the low springrate and low damping rate characteristics of the LIVE unit portion.

One such patent application is U.S. Patent Publication No. 2015/0369326,filed by Modrezejewski, et al., and entitled “Rotating Shaft DampingWith Electro-Rheological Fluid”. Briefly, these applicants teachrotating shaft damping using an electro-rheological fluid. At least aportion of a circumferential surface area of a portion of a rotorcraftrotating shaft is surrounded with multiple hollow members, and eachhollow member includes an electro-rheological fluid having a viscositythat changes based on an electric field applied to theelectro-rheological fluid. The vibration of the rotorcraft rotatingshaft is controlled by changing the viscosity of the electro-rheologicalfluid in response to the electric field applied to theelectro-rheological fluid.

Yet another application is U.S. Patent Publication No. 2008/0173754,filed by Strehlow, et al., and is entitled “Method For Damping RearExtension Arm Vibrations Of Rotorcraft And Rotorcraft With A RearExtension Arm Vibration Damping Device”. Briefly, these applicants aresaid to teach a method for damping vibrations in a tail boom of arotary-wing aircraft includes the steps of detecting tail boomvibrations induced by external vibration excitation, and generating andintroducing strains into the tail boom based on the detected tail boomvibrations. Next, strains are applied over a surface area and areout-of-phase with respect to the detected tail boom vibrations so as todamp the externally excited induced tail boom vibrations. In addition, arotary-wing aircraft, includes a fuselage, a cockpit area integratedinto the fuselage, a tail boom arranged on the fuselage and a tail boomvibration-damping device. The vibration-damping device includes at leastone sensor element configured to detect tail boom vibrations induced byexternal vibration excitation and at least one actuator configured togenerate and introduce strains into the tail boom that are out-of-phasewith respect to the induced tail boom vibrations, the actuator beingfunctionally coupled to the sensor element, engaging with a tail boomstructure at one side of the tail boom, and forming a flat-surfaced bondwith the tail boom.

SUMMARY OF THE INVENTION

In one embodiment, the present invention includes a damper assembly foran airframe comprising: a mass to damp the vibration of the airframe;one or more wire rope isolators having a first and a second portion,wherein the mass is attached to the one or more wire rope isolators andthe mass is isolated from the airframe by the one or more wire ropeisolators;

and a first fastener and a second fastener, wherein the first fastenersattaches to the first portion of the wire rope isolator to the mass, andthe second fastener attaches the second portion of the wire ropeisolator to the airframe to dampen vibration of the airframe. In oneaspect, the wire rope isolators are further defined as comprising astiffness, compression/shear, compression/roll, and shape, wherein thestiffness, compression/shear, compression/roll, and shape of the wirerope is selected to provide frequency isolation of the mass in two ormore frequencies. In another aspect, the first fastener or the secondfastener is selected to attach the damper assembly to a rotorcraft orvertical take off and landing craft. In another aspect, the first andsecond portions of the one or more wire rope isolators are along a sideof the one or more wire rope isolators, at the ends of the one or morewire rope isolators, at the end and/or along the side of the one or morewire rope isolators. In another aspect, the mass is connected by 2, 3,4, 5, 6, 7, 8, 9, 10, 11, 12, or more wire rope isolators that arepositioned on one or more sides of the mass. In another aspect, the massis positioned within an airframe, as the end of the airframe, at the endof a tail boom, along the length of a tail boom, or a combinationthereof. In another aspect, the damper assembly is a passive damperassembly. In another aspect, the damper assembly further comprises acoating on the mass, the first or second fasteners, and/or the one ormore wire rope isolators. In another aspect, the mass, the first orsecond fasteners, or the one or more wire rope isolators are selectedfrom at least one of metal, composite, polymer, ceramic, alloys, orcombinations of the same. In another aspect, the wire rope isolators aredefined further as comprising one or more of fiber strands, fiber wires,polymer strands, polymer wires, lubricating oil, polymer, adhesive,filler, and/or a coating. In another aspect, the wire rope is selectedfrom a size, shape, and strength of the wire rope in one or moredimensions based on at least one of: (1) a rope bending length l; (2) adiameter D of sheave and/or drum; (3) one or more simple bendings perworking cycle w-sim; (4) one or more reverse bendings per working cyclew-rev; (5) a combined fluctuating tension and bending per working cyclew-com; (6) a relative fluctuating tensile force deltaS/S; or (7) a ropetensile force S. In another aspect, the vibration is adjusted in two ormore frequencies based on the shape, size, compressive strength,rotational strength, or pull strength of the wire rope.

In another embodiment, the present invention includes a method fordamping vibration of an airframe comprising: providing a mass to dampenthe vibration of the airframe; selecting one or more wire rope isolatorshaving a first and a second portion, wherein the mass is isolated fromthe airframe by the one or more wire rope isolators; and attaching themass to the one or more wire rope isolators and the one or more wirerope isolators to an airframe, wherein one or more first fastenersattach the first portion of the one or more wire rope isolators to themass, and one or more second fasteners attach the second portion of theone or more wire rope isolators to the airframe, wherein the massdampens vibration of the airframe. In one aspect, the wire ropeisolators are further defined as comprising a stiffness,compression/shear, compression/roll, and shape, wherein the stiffness,compression/shear, compression/roll, and shape of the wire rope isselected to provide frequency isolation of the mass in two or morefrequencies. In another aspect, the first fastener or the secondfastener is selected to attach the damper assembly to a rotorcraft orvertical take off and landing craft. In another aspect, the first andsecond portions of the one or more wire rope isolators are along a sideof the one or more wire rope isolators, at the ends of the one or morewire rope isolators, at the end and/or along the side of the one or morewire rope isolators. In another aspect, the mass is connected by 2, 3,4, 5, 6, 7, 8, 9, 10, 11, 12, or more wire rope isolators that arepositioned on one or more sides of the mass. In another aspect, the massis positioned within an airframe, as the end of the airframe, at the endof a tail boom, along the length of a tail boom, or a combinationthereof. In another aspect, the damper assembly is a passive damperassembly. In another aspect, the method further comprises coating one ormore of the mass, the first or second fasteners, or the one or more wirerope isolators. In another aspect, the mass, the first or secondfasteners, or the one or more wire rope isolators are selected from atleast one of metal, composite, polymer, ceramic, alloys, or combinationsof the same. In another aspect, the wire rope isolators are definedfurther as comprising one or more of fiber strands, fiber wires, polymerstrands, polymer wires, lubricating oil, polymer, adhesive, filler,and/or a coating. In another aspect, the wire rope is selected from asize, shape, and strength of the wire rope in one or more dimensionsbased on at least one of: (1) a rope bending length l; (2) a diameter Dof sheave and/or drum; (3) one or more simple bendings per working cyclew-sim; (4) one or more reverse bendings per working cycle w-rev; (5) acombined fluctuating tension and bending per working cycle w-com; (6) arelative fluctuating tensile force deltaS/S; or (7) a rope tensile forceS. In another aspect, the vibration is adjusted in two or morefrequencies based on the shape, size, compressive strength, rotationalstrength, or pull strength of the wire rope.

In another embodiment, the present invention includes a mass damper kitfor an airframe comprising: a mass selected to dampen the vibration ofthe airframe; one or more wire rope isolators having a first and asecond portion, wherein the one or more wire rope isolators are selectedto dampen airframe vibration; and one or more first fasteners and one ormore second fasteners, wherein the one or more first fasteners areadapted to attach the first portion of the wire rope isolator to themass, and the one or more second fasteners are adapted to attach thesecond portion of the wire rope isolator to the airframe to dampenvibration of the airframe; and instructions to attach the mass to theone or more wire rope isolators via the one or more first fasteners andone or more wire rope isolators via the second fasteners to theairframe.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the features and advantages of thepresent invention, reference is now made to the detailed description ofthe invention along with the accompanying figures and in which:

FIG. 1 shows a side view of a helicopter according to a preferredembodiment of the present application;

FIGS. 2A and 2B show a perspective view of tiltrotor aircraft accordingto an alternative embodiment of the present application;

FIG. 3 shows a tail boom of a rotorcraft and FIG. 3A is a close-up viewof the tail section of the tail boom showing one configuration of thedamper of the present invention;

FIG. 4A shows a side view of the end of the tail boom and oneconfiguration of the damper positioned at the end of the tail boom;

FIG. 4B shows a top view of the end of the tail boom and oneconfiguration of the damper positioned at the end of the tail boom;

FIG. 5 shows an isometric view of the end of the tail boom and oneconfiguration of the damper positioned at the end of the tail boom;

FIG. 6 shows a side view of a helicopter that shows potential locationfor the damper of the present invention;

FIG. 7A shows a diagram of a side view of one configuration of thedamper of the present invention;

FIG. 7B shows a diagram of a side view of one configuration of thedamper of the present invention;

FIG. 7C shows a diagram of a side view of one configuration of thedamper of the present invention;

FIG. 8A shows a diagram of an end view of one configuration of thedamper of the present invention;

FIG. 8B shows a diagram of an end view of one configuration of thedamper of the present invention;

FIG. 9A shows a diagram of a side view of one configuration of thedamper of the present invention;

FIG. 9B shows a diagram of a side view of one configuration of thedamper of the present invention;

FIG. 10A shows a diagram of a side view of one configuration of thedamper of the present invention;

FIG. 10B shows a diagram of a side view of one configuration of thedamper of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Illustrative embodiments of the system of the present application aredescribed below. In the interest of clarity, not all features of anactual implementation are described in this specification. It will ofcourse be appreciated that in the development of any such actualembodiment, numerous implementation-specific decisions must be made toachieve the developer's specific goals, such as compliance withsystem-related and business-related constraints, which will vary fromone implementation to another. Moreover, it will be appreciated thatsuch a development effort might be complex and time-consuming but wouldnevertheless be a routine undertaking for those of ordinary skill in theart having the benefit of this disclosure.

In the specification, reference may be made to the spatial relationshipsbetween various components and to the spatial orientation of variousaspects of components as the devices are depicted in the attacheddrawings. However, as will be recognized by those skilled in the artafter a complete reading of the present application, the devices,members, apparatuses, etc. described herein may be positioned in anydesired orientation. Thus, the use of terms such as “above,” “below,”“upper,” “lower,” or other like terms to describe a spatial relationshipbetween various components or to describe the spatial orientation ofaspects of such components should be understood to describe a relativerelationship between the components or a spatial orientation of aspectsof such components, respectively, as the device described herein may beoriented in any desired direction.

The present invention is a passive vibration dampening device that isattached with wire ropes to the frame of a craft, such as an aircraft.Non-limiting examples of aircrafts include rotorcraft, such ashelicopters and vertical take off and landing aircraft. Briefly, themoving mass is excited by a given source, typically the vibrationalforcing from rotor blades, which in turn provides damping for a criticalmode placed very near a known excitation frequency. This reduces thevibration levels at that frequency felt throughout the aircraft.

As used herein, the term “wire rope” refers to one or more ropes withstrands of metal or steel wire laid or twisted into a shape around acore. The cross-sectional shape of the wires can be, for example, round,ovoid, trapezoidal, square, rectangular, triangular, or combinationsthereof. The wire rope may also include a “core”, which can be one ofthree types: (1) a fiber core, made up of synthetic or natural material(fiber cores are generally the most flexible and elastic, but are easilycrushed and thus not suitable for heavy loads); (2) a wire strand core,is made up of one additional strand of wire, and is typically used forsuspension; and (3) an independent wire rope core, which is the mostdurable in all types of environments, or combinations thereof. The oneor more wires of the wire rope are typically made of non-alloy carbonsteel although other suitable materials may be used such as steel, iron,stainless steel, chromium steel, galvanized steel, alloys, monel, andbronze materials. Wires may be made by suitable methods, such as thedrawing process where the wire cross-section is reduced in stages, forexample in multiple stages, e.g., from 0.1 mm to 10 mm diameter. Using adrawing process, the nominal strength of the wire may be increased.

The type and material of the wire rope can be selected to selectdifferent compression, tensile strength, flexure, or any parameter inthree dimensions, including using different types of wire rope within asingle wire rope assembly. Non-limiting examples of wire rope includethose that are: (1) stranded ropes (aka running ropes) that are formedby bending over sheaves and cylinders and are stressed mainly by bendingand secondly by tension; (2) stationary ropes or stay ropes (spiralropes, e.g., full-locked), which carry tensile forces and are thereforemainly loaded by static and fluctuating tensile stresses; (3) trackropes (aka full locked ropes) generally do not take on the curvature ofany rollers and under the roller force, a so-called free bending radiusof the rope occurs, which radius increases (and the bending stressesdecrease) with the tensile force and decreases with the roller force;and/or (4) wire rope slings (aka stranded ropes), which are slings thatare stressed by tensile forces but first of all by bending stresses whenbent over more or less sharp edges. In particular, one or more of thefollowing factors can be varied to optimize the dampening effect causedby the wire rope, including: (1) working cycles up to rope discarding orbreakage (mean or 10% limit); (2) number of wire breaks (detection toneed rope replacement); (3) rope safety factor (minimum breaking forceFmin/nominal rope tensile force S), which is the ability to resistextreme impact forces; (4) Donandt force (yielding tensile force for agiven bending diameter ratio D/d), generally, the nominal rope tensileforce S is smaller than the Donandt force SD1; and (5) rope diameter(maximum rope endurance for a given sheave diameter D and tensile ropeforce S).

FIG. 1 depicts an aircraft 100 in accordance with a preferred embodimentof the present application. In the exemplary embodiment, aircraft 100 isa helicopter having a fuselage 102 and a rotor system 104 carriedthereon. A plurality of rotor blades 106 is operably associated withrotor system 104 for creating flight. The system of the presentinvention can be used in conjunction with an aircraft 100. Althoughshown associated with a helicopter, it will be appreciated that thesystem of the present application could also be utilized with differenttypes of rotary aircraft and vehicles.

For example, FIG. 2A illustrates a tiltrotor aircraft 200 that utilizesthe system in accordance with the present application. Tiltrotoraircraft 200 includes rotor assemblies 202 a and 202 b that are carriedby wings 204 a and 204 b, and are disposed at end portions 206 a and 206b of wings 204 a and 204 b, respectively. Rotor assemblies 202 a and 202b include nacelles 208 a and 208 b, which carry the engines andtransmissions of tiltrotor aircraft 200. Tilt rotor assemblies 202 a and202 b move or rotate relative to wing members 204 a and 204 b between ahelicopter or hover mode in which tilt rotor assemblies 202 a and 202 bare tilted upward, such that tiltrotor aircraft 200 flies like aconventional helicopter; and an airplane or cruise mode in which tiltrotor assemblies 202 a and 202 b are tilted forward, such that tiltrotoraircraft 200 flies like a conventional propeller driven aircraft.

FIG. 2B illustrates another tiltrotor aircraft 200 that utilizes thesystem in accordance with the present application. Tiltrotor aircraft200 includes rotor assemblies 202 a and 202 b that are carried by wings204 a and 204 b, and are disposed at end portions 206 a and 206 b ofwings 204 a and 204 b, respectively. Rotor assemblies 202 a and 202 binclude nacelles 208 a and 208 b, which include the engines andtransmissions of tiltrotor aircraft 200. In this embodiment, the enginesare fixed to the wing and do not rotate, rather, only the pylons 210 aand 210 b with the rotor assemblies 202 a and 202 b rotates. Tilt rotorassemblies 202 a and 202 b move and rotate relative to wing members 204a and 204 b and the nacelles 208 a and 208 b. The tilt rotor assemblies202 a and 202 b do not move relative to the wing members 204 a and 204b. Instead, during the transition between a helicopter or hover modeonly the pylons 210 a and 210 b with the rotor assemblies 202 a and 202b rotate to redirect the thrust from the rotor assemblies 202 a and 202b. The rotorcraft 200 is still able to fly like a conventionalhelicopter; and an airplane or cruise mode in which on the rotors aretilted forward, such that tiltrotor aircraft 200 flies like aconventional propeller driven aircraft.

FIG. 3 shows a damper system 300 on a tail boom 302 of a rotorcraft anda close-up view of a tail section 304 at the end of the tail boom 302showing one configuration of the wire rope damper assembly 306 of thepresent invention. In FIG. 3A, the close-up view, the damper assembly306 is attached to the distal end 308 of the tail boom 302, and includesa mass 310, wire ropes 312 a, 312 b, first fasteners 314 a, 314 b, andsecond fasteners 316 a, 316 b. The mass 310 is attached to the wireropes 312 a, 312 b via first fasteners 314 a, 314 b, and the wire ropes312 a, 312 b are connected to the distal end 308 of the tail boom 302via second fasteners 316 a, 316 b. Thus, the wire ropes 312 a, 312 bisolate the mass 310 from the distal end 308 of the tail boom 302.

FIG. 4A shows a side view of the distal end 308 of the tail boom 302 andone configuration of the wire rope damper assembly 306 attached to thetail rotor gearbox support structure. In this side view, the damperassembly 306 is attached to the distal end 308 of the tail boom 302, andincludes a mass 310, wire ropes 312 a, 312 b, first fasteners 314 a, 314b, and second fasteners 316 a, 316 b. The mass 310 is attached to thewire ropes 312 a, 312 b via first fasteners 314 a, 314 b, and the wireropes 312 a, 312 b are connected to the distal end 308 of the tail boom302 via second fasteners 316 a, 316 b, all of which are attached bybolts 318. Thus, the wire ropes 312 a, 312 b isolate the mass 310 fromthe distal end 308 of the tail boom 302, and further include a plate320, which can provide additional surface to attach the damper assembly306 to the distal end 308, which distal end 308 is often open to reducethe mass of the airframe.

FIG. 4B shows a top view of the distal end 308 of the tail boom 302 andone configuration of the wire rope damper assembly 306. In this topview, the damper assembly 306 is attached to the distal end 308 of thetail boom 302, and includes a mass 310, wire ropes 312 a, 312 b, 312 c,312 d, first fasteners 314 a, 314 b, 314 c, and 314 d, and secondfasteners 316 a, 316 b. The mass 310 is attached to the wire ropes 312a, 312 b, 312 c, 312 d via first fasteners and the wire ropes 312 a, 312b, 312 c, 312 d are connected to the distal end 308 of the tail boom 302via second fasteners. Thus, the wire ropes 312 a, 312 b, 312 c, 312 disolate the mass 310 from the distal end 308 of the tail boom 302.

In FIGS. 4A and 4B, the damper assembly 306 is located at the aft-mostend of the tail boom, which attached to the tail rotor gearbox supportairframe structure, however, the exact position for different rotorcraftcan be selected for convenience and/or effectiveness.

While there is no specific requirement on location, the damper assemblycan work at multiple locations throughout the aircraft, with one factorbeing that the attaching structure must be stiff enough (of additionalstiffening added) to support the damper assembly of the presentinvention.

FIG. 5 shows an isometric view of the distal end 308 of the tail boom302 and one configuration of the wire rope damper assembly 306. In thistop view, the damper assembly 306 is attached to the distal end 308 ofthe tail boom 302, and includes a mass 310, wire ropes 312 b, 312 c, 312d, first fasteners 314 b, and second fasteners 316 a, 316 b. The mass310 is attached to the wire ropes 312 b, 312 c, 312 d via firstfasteners 314 b and the wire ropes 312 b, 312 c, 312 d are connected tothe distal end 308 of the tail boom 302 via second fasteners 316 b, 316c, and 316 d. Thus, the wire ropes 312 b, 312 c, 312 d isolate the mass310 from the distal end 308 of the tail boom 302.

FIG. 6 shows a side view of a helicopter airframe 400 that showspotential location for on or more damper assemblies 402, 404, 406, or408 of the present invention.

FIG. 7A shows a diagram of an exploded side view of one configuration ofthe damper assembly 306 of the present invention, which is attached tothe tail boom 302. In this configuration, one portion of the wire rope312 is connected via plate 320 to the tail boom 302, and the portion ofthe wire rope 312 is connected via plate 322 to the mass 310. In thisconfiguration, the wire rope isolator is providing isolation based onshear.

FIG. 7B shows a diagram of a side view of another configuration of thedamper assembly 306 of the present invention, which is attached to thetail boom 302. In this configuration, the tail boom 302 is shown in aside view, while the damper assembly 306 is shown as an end-view of thetail boom 302. The mass 310 is depicted as inside the tail boom 302,with the wire ropes 312 a, 312 b, 312 c, and 312 d support the mass 310within the tail boom 302. Alternatively, the same configuration of thedamper assembly 306 could be fitted within a frame positioned, andconnected to, the distal end 308 of the tail boom 302. For example, inthis configuration, the wire rope isolators dampen based on, e.g., 45degree compression and/or roll.

FIG. 7C shows a diagram of a side view of another configuration of thedamper assembly 306 of the present invention, which is attached to thetail boom 302, and in which the mass is the tail ballast. In thisconfiguration, the wire rope 312 is connected to plate 320 and plate322, one of which is attached to the mass 310, and the mass ispositioned below the plate and wire assembly 324. In this configuration,the wire rope isolators dampen based on compression.

FIG. 8A shows a diagram of an end view of one configuration of thedamper assembly 306 within the tail boom 302. The mass 310 is depictedin the center of the tail boom 302, and the mass 310 is shown attachedto the wire ropes 312 a, 312 b, 312 c, and 312 d via plates 320 a, 320b, 320 c, and 320 d, and the wire ropes 312 a, 312 b, 312 c, and 312 dare attached to the tail boom via plates 322 a, 322 b, 322 c, and 322 d.In this configuration, the plates 320 a-320 d and 322 a-322 d areattached to the sides of wire ropes 312 a-d, which provide for isolationin different directions, e.g., along the longitudinal axis of the wireropes 312 a-d, and based on the stiffness of the overall wire ropes 312a-312 d, all of which can be optimized to maximize the dampening ofvibrations by the mass 310. In this configuration, the longitudinal axisof the wire ropes 312 a-312 d are depicted as being generallyperpendicular to the longitudinal axis of the tail boom 302, however,the skilled artisan will recognize that the longitudinal axis of thewire ropes 312 a-312 d can be varied in relation to the longitudinalaxis of the tail boom 302 for each of wire ropes 312 a-312 d. In thisconfiguration, the wire rope isolators can be a compact rope isolatorthat each provide dampening based on both compression and shear.

FIG. 8B shows a diagram of an end view of one configuration of thedamper assembly 306 within the tail boom 302. The mass 310 is depictedin the center of the tail boom 302, and the mass 310 is shown attachedto the wire ropes 312 a, 312 b, 312 c, and 312 d via plates 320 a, 320b, 320 c, and 320 d, and the wire ropes 312 a, 312 b, 312 c, and 312 dare attached to the tail boom. In this configuration, the plates 320a-320 d are attached to the sides of wire ropes 312 a-312 d, whichprovide for isolation in different directions, e.g., along thelongitudinal axis of the wire ropes 312 a-312 d, and based on thestiffness of the overall wire ropes 312 a-312 d, all of which can beoptimized to maximize the dampening of vibrations by the mass 310. Inthis configuration, the longitudinal axis of the wire ropes 312 a-312 dare depicted as being generally parallel to the longitudinal axis of thetail boom 302, however, the skilled artisan will recognize that thelongitudinal axis of the wire ropes 312 a-312 d can be varied inrelation to the longitudinal axis of the tail boom 302 for each of wireropes 312 a-312 d. In this configuration, the wire rope isolators can bea wire rope isolator that each provide dampening based on bothcompression and roll.

FIG. 9A shows a diagram of a side view of one configuration of thedamper assembly 306 of the present invention connected to an airframe700. In this configuration, the damper assembly 306 includes the mass310 (which can be, e.g., the tail ballast) that is connected via wireropes 312 a, 312 b and first fasteners 314 a, 314 b. The wire ropes 312a, 312 b are connected to the airframe 700 via second fasteners 316 a,316 b. In this configuration, the mass 310 is cantilevered.

FIG. 9B shows a diagram of a side view of one configuration of thedamper assembly 306 of the present invention connected to an airframe700. In this configuration, the damper assembly 306 includes the mass310 (which can be, e.g., the tail ballast) that is located between pairsof wire ropes 312 a, 312 b and 312 c, 312 d and first fasteners 314 a,314 b, 314 c, 314 d. The pairs of wire ropes 312 a, 312 b and 312 c areconnected to the airframe 700 via second fasteners 316 a, 316 b, 316 c,316 d. In this configuration, the mass 310 is supported on both sides.

FIG. 10A shows a diagram of a side view of another configuration of thedamper assembly 306 of the present invention connected to an airframe700 via plate 320. In this configuration, the damper assembly 306includes the mass 310 (which can be, e.g., the tail ballast) that isconnected via wire ropes 312 a, 312 b and first fasteners 314 a, 314 bto the plate 320. The plate 320 is attached to the airframe 700. Themass 310 is connected to the wire ropes 312 a, 312 b via secondfasteners 316 a, 316 b along a narrow portion of the wire ropes 312 a,312 b.

FIG. 10B shows a diagram of a side view of configuration of the damperassembly 306 of the present invention connected to an airframe 700, butin which the wider portion of the wire ropes 312 a, 312 b is attached tothe mass 310. In this configuration, the damper assembly 306 includesthe mass 310 (which can be, e.g., the tail ballast) that is locatedbetween pairs of wire ropes 312 a, 312 b and 312 c, 312 d and firstfasteners 314 a, 314 b, 314 c, 314 d. The pairs of wire ropes 312 a, 312b and 312 c are connected to the airframe 700 via second fasteners 316a, 316 b, 316 c, 316 d.

The present invention can use wire rope isolators, such as those taughtin, e.g., U.S. Pat. Nos. 6,406,011, 5,549,285, and 6,290,217, owned byEnidine, Inc., relevant portions and figures incorporated herein byreference.

It will be understood that particular embodiments described herein areshown by way of illustration and not as limitations of the invention.The principal features of this invention can be employed in variousembodiments without departing from the scope of the invention. Thoseskilled in the art will recognize, or be able to ascertain using no morethan routine experimentation, numerous equivalents to the specificprocedures described herein. Such equivalents are considered to bewithin the scope of this invention and are covered by the claims.

All publications and patent applications mentioned in the specificationare indicative of the level of skill of those skilled in the art towhich this invention pertains. All publications and patent applicationsare herein incorporated by reference to the same extent as if eachindividual publication or patent application was specifically andindividually indicated to be incorporated by reference.

The use of the word “a” or “an” when used in conjunction with the term“comprising” in the claims and/or the specification may mean “one,” butit is also consistent with the meaning of “one or more,” “at least one,”and “one or more than one.” The use of the term “or” in the claims isused to mean “and/or” unless explicitly indicated to refer toalternatives only or the alternatives are mutually exclusive, althoughthe disclosure supports a definition that refers to only alternativesand “and/or.” Throughout this application, the term “about” is used toindicate that a value includes the inherent variation of error for thedevice, the method being employed to determine the value, or thevariation that exists among the study subjects.

As used in this specification and claim(s), the words “comprising” (andany form of comprising, such as “comprise” and “comprises”), “having”(and any form of having, such as “have” and “has”), “including” (and anyform of including, such as “includes” and “include”) or “containing”(and any form of containing, such as “contains” and “contain”) areinclusive or open-ended and do not exclude additional, unrecitedelements or method steps. In embodiments of any of the compositions andmethods provided herein, “comprising” may be replaced with “consistingessentially of” or “consisting of”. As used herein, the phrase“consisting essentially of” requires the specified integer(s) or stepsas well as those that do not materially affect the character or functionof the claimed invention. As used herein, the term “consisting” is usedto indicate the presence of the recited integer (e.g., a feature, anelement, a characteristic, a property, a method/process step or alimitation) or group of integers (e.g., feature(s), element(s),characteristic(s), propertie(s), method/process steps or limitation(s))only.

The term “or combinations thereof” as used herein refers to allpermutations and combinations of the listed items preceding the term.For example, “A, B, C, or combinations thereof” is intended to includeat least one of: A, B, C, AB, AC, BC, or ABC, and if order is importantin a particular context, also BA, CA, CB, CBA, BCA, ACB, BAC, or CAB.Continuing with this example, expressly included are combinations thatcontain repeats of one or more item or term, such as BB, AAA, AB, BBC,AAABCCCC, CBBAAA, CABABB, and so forth. The skilled artisan willunderstand that typically there is no limit on the number of items orterms in any combination, unless otherwise apparent from the context.

As used herein, words of approximation such as, without limitation,“about”, “substantial” or “substantially” refers to a condition thatwhen so modified is understood to not necessarily be absolute or perfectbut would be considered close enough to those of ordinary skill in theart to warrant designating the condition as being present. The extent towhich the description may vary will depend on how great a change can beinstituted and still have one of ordinary skilled in the art recognizethe modified feature as still having the required characteristics andcapabilities of the unmodified feature. In general, but subject to thepreceding discussion, a numerical value herein that is modified by aword of approximation such as “about” may vary from the stated value byat least ±1, 2, 3, 4, 5, 6, 7, 10, 12 or 15%.

All of the devices and/or methods disclosed and claimed herein can bemade and executed without undue experimentation in light of the presentdisclosure. While the devices and/or and methods of this invention havebeen described in terms of preferred embodiments, it will be apparent tothose of skill in the art that variations may be applied to thecompositions and/or methods and in the steps or in the sequence of stepsof the method described herein without departing from the concept,spirit and scope of the invention. All such similar substitutes andmodifications apparent to those skilled in the art are deemed to bewithin the spirit, scope and concept of the invention as defined by theappended claims.

Furthermore, no limitations are intended to the details of constructionor design herein shown, other than as described in the claims below. Itis therefore evident that the particular embodiments disclosed above maybe altered or modified and all such variations are considered within thescope and spirit of the disclosure. Accordingly, the protection soughtherein is as set forth in the claims below.

To aid the Patent Office, and any readers of any patent issued on thisapplication in interpreting the claims appended hereto, applicants wishto note that they do not intend any of the appended claims to invokeparagraph 6 of 35 U.S.C. § 112 as it exists on the date of filing hereofunless the words “means for” or “step for” are explicitly used in theparticular claim.

1. A damper assembly for an airframe comprising: a mass to damp thevibration of the airframe; one or more wire rope isolators having afirst and a second portion, wherein the mass is attached to the one ormore wire rope isolators and the mass is isolated from the airframe bythe one or more wire rope isolators, wherein the wire rope isolators areselected to adjust to two or more vibration frequencies; and a firstfastener and a second fastener, wherein the first fasteners attaches tothe first portion of the wire rope isolator to the mass, and the secondfastener attaches the second portion of the wire rope isolator to theairframe to dampen vibration of the airframe.
 2. The damper assembly ofclaim 1, wherein the wire rope isolators are further defined ascomprising a stiffness, compression/shear, compression/roll, and shape,wherein the stiffness, compression/shear, compression/roll, and shape ofthe wire rope isolator is selected to provide frequency isolation of themass in two or more frequencies.
 3. The damper assembly of claim 1,wherein the first fastener or the second fastener is selected to attachthe damper assembly to a rotorcraft or vertical take off and landingcraft.
 4. The damper assembly of claim 1, wherein the first and secondportions of the one or more wire rope isolators are along a side of theone or more wire rope isolators, at the ends of the one or more wirerope isolators, at the end and/or along the side of the one or more wirerope isolators.
 5. The damper assembly of claim 1, wherein the mass isconnected by 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, or more wire ropeisolators that are positioned on one or more sides of the mass.
 6. Thedamper assembly of claim 1, wherein the mass is positioned within theairframe, as an end of the airframe, at an end of a tail boom, along alength of a tail boom, or a combination thereof.
 7. The damper assemblyof claim 1, wherein the damper assembly is a passive damper assembly. 8.The damper assembly of claim 1, further comprising a coating on themass, the first or second fasteners, and/or the one or more wire ropeisolators.
 9. The damper assembly of claim 1, wherein the mass, thefirst or second fasteners, or the one or more wire rope isolators areselected from at least one of metal, composite, polymer, ceramic,alloys, or combinations of the same.
 10. The damper assembly of claim 1,wherein the wire rope isolators are defined further as comprising one ormore of fiber strands, fiber wires, polymer strands, polymer wires,lubricating oil, polymer, adhesive, filler, and/or a coating.
 11. Thedamper assembly of claim 1, wherein the wire rope isolator is selectedfrom a size, shape, and strength of the wire rope in one or moredimensions based on at least one of: (1) a rope bending length l; (2) adiameter D of sheave and/or drum; (3) one or more simple bendings perworking cycle w-sim; (4) one or more reverse bendings per working cyclew-rev; (5) a combined fluctuating tension and bending per working cyclew-com; (6) a relative fluctuating tensile force deltaS/S; or (7) a ropetensile force S.
 12. The damper assembly of claim 1, wherein thevibration is adjusted in two or more frequencies based on the shape,size, compressive strength, rotational strength, or pull strength of thewire rope isolator.
 13. A method for damping vibration of an airframecomprising: providing a mass to dampen the vibration of the airframe;selecting one or more wire rope isolators having a first and a secondportion, wherein the mass is isolated from the airframe by the one ormore wire rope isolators, wherein the wire rope isolators are selectedto adjust to two or more vibration frequencies; and attaching the massto the one or more wire rope isolators and the one or more wire ropeisolators to the airframe, wherein one or more first fasteners attachthe first portion of the one or more wire rope isolators to the mass,and one or more second fasteners attach the second portion of the one ormore wire rope isolators to the airframe, wherein the mass dampensvibration of the airframe.
 14. The method of claim 13, wherein the wirerope isolators are further defined as comprising a stiffness,compression/shear, compression/roll, and shape, wherein the stiffness,compression/shear, compression/roll, and shape of the wire rope isolatoris selected to provide frequency isolation of the mass in two or morefrequencies.
 15. The method of claim 13, wherein the first fastener orthe second fastener is selected to attach the damper assembly to arotorcraft or vertical take off and landing craft.
 16. The method ofclaim 13, wherein the first and second portions of the one or more wirerope isolators are along a side of the one or more wire rope isolators,at the ends of the one or more wire rope isolators, at the end and/oralong the side of the one or more wire rope isolators.
 17. The method ofclaim 13, wherein the mass is connected by 2, 3, 4, 5, 6, 7, 8, 9, 10,11, 12, or more wire rope isolators that are positioned on one or moresides of the mass.
 18. The method of claim 13, wherein the mass ispositioned within the airframe, as an end of the airframe, at the an ofa tail boom, along a length of a tail boom, or a combination thereof.19. The method of claim 13, wherein the damper assembly is a passivedamper assembly.
 20. The method of claim 13, further comprising coatingone or more of the mass, the first or second fasteners, or the one ormore wire rope isolators.
 21. The method of claim 13, wherein the mass,the first or second fasteners, or the one or more wire rope isolatorsare selected from at least one of metal, composite, polymer, ceramic,alloys, or combinations of the same.
 22. The method of claim 13, whereinthe wire rope isolators are defined further as comprising one or more offiber strands, fiber wires, polymer strands, polymer wires, lubricatingoil, polymer, adhesive, filler, and/or a coating.
 23. The method ofclaim 13, wherein the wire rope isolator is selected from a size, shape,and strength of the wire rope in one or more dimensions based on atleast one of: (1) a rope bending length l; (2) a diameter D of sheaveand/or drum; (3) one or more simple bendings per working cycle w-sim;(4) one or more reverse bendings per working cycle w-rev; (5) a combinedfluctuating tension and bending per working cycle w-com; (6) a relativefluctuating tensile force deltaS/S; or (7) a rope tensile force S. 24.The method of claim 13, wherein the vibration is adjusted in two or morefrequencies based on the shape, size, compressive strength, rotationalstrength, or pull strength of the wire rope isolator.
 25. A mass damperkit for an airframe comprising: a mass selected to dampen the vibrationof the airframe; one or more wire rope isolators having a first and asecond portion, wherein the one or more wire rope isolators are selectedto dampen airframe vibration, wherein the wire rope isolators areselected to adjust to two or more vibration frequencies; and one or morefirst fasteners and one or more second fasteners, wherein the one ormore first fasteners are adapted to attach the first portion of the wirerope isolator to the mass, and the one or more second fasteners areadapted to attach the second portion of the wire rope isolator to theairframe to dampen vibration of the airframe; and instructions to attachthe mass to the one or more wire rope isolators via the one or morefirst fasteners and one or more wire rope isolators via the secondfasteners to the airframe.